An NFS client that mounts multiple exports from the same NFSserver with higher NFSv4 versions disabled (i.e. 4.2) and withoutforcing a specific NFS version results in fscache index cookiecollisions and the following messages:[ 570.004348] FS-Cache: Duplicate cookie detected

Each nfs_client structure should have its own fscache index cookie,so add the minorversion to nfs_server_key.